Yes Mr. Mayor, the city IS on fire.
There isn't really much to review. You are the mayor of your own city. Better yet, you are the mayor of multiple cities in a larger region.
This game can be easy, or very challenging depending on how you play it. It's challenging enough that an experienced city builder must try hard to manage everything to build a working, well balanced, advancing city. Yet, the game is easy enough for beginners to learn, and start working there way up to bigger and bigger cities.
There is really only one game mode, and you build cities. But inside this mode there are three aspects. The god mode aspect where you get to control and edit the terrain and create your disasters (which can be really fun). Then there is the build mode, where you zone your city, provide proper transportation and make sure that all the sims in your city have the amenities that they need to survive.
The third mode is the mode where you can actually control (very little amount of control) some of the sims in your city, and you can drive some of the vehicles.
Now this is great by itself, but the huge community makes it even better. There are literally thousands of addon's and mod's that make the game more realistic or more rediculous depending on what you are going for. You can add multiple styles of buildings, add a mod the reduces pollution or increases money, and you can change basically every aspect inside this game.
If you are an experienced city builder and don't have this game, then you definitely should have it. If you are a beginner, wanting to get into city building games, then this is the first and only game that you should start with.